1 /*
2 * Copyright (c) 2013 The WebM project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10 #include "./vpx_config.h"
11 #include "./bitreader_buffer.h"
12
vpx_rb_bytes_read(struct vpx_read_bit_buffer * rb)13 size_t vpx_rb_bytes_read(struct vpx_read_bit_buffer *rb) {
14 return (rb->bit_offset + 7) >> 3;
15 }
16
vpx_rb_read_bit(struct vpx_read_bit_buffer * rb)17 int vpx_rb_read_bit(struct vpx_read_bit_buffer *rb) {
18 const size_t off = rb->bit_offset;
19 const size_t p = off >> 3;
20 const int q = 7 - (int)(off & 0x7);
21 if (rb->bit_buffer + p < rb->bit_buffer_end) {
22 const int bit = (rb->bit_buffer[p] >> q) & 1;
23 rb->bit_offset = off + 1;
24 return bit;
25 } else {
26 rb->error_handler(rb->error_handler_data);
27 return 0;
28 }
29 }
30
vpx_rb_read_literal(struct vpx_read_bit_buffer * rb,int bits)31 int vpx_rb_read_literal(struct vpx_read_bit_buffer *rb, int bits) {
32 int value = 0, bit;
33 for (bit = bits - 1; bit >= 0; bit--)
34 value |= vpx_rb_read_bit(rb) << bit;
35 return value;
36 }
37
vpx_rb_read_signed_literal(struct vpx_read_bit_buffer * rb,int bits)38 int vpx_rb_read_signed_literal(struct vpx_read_bit_buffer *rb,
39 int bits) {
40 const int value = vpx_rb_read_literal(rb, bits);
41 return vpx_rb_read_bit(rb) ? -value : value;
42 }
43
vpx_rb_read_inv_signed_literal(struct vpx_read_bit_buffer * rb,int bits)44 int vpx_rb_read_inv_signed_literal(struct vpx_read_bit_buffer *rb,
45 int bits) {
46 #if CONFIG_MISC_FIXES
47 const int nbits = sizeof(unsigned) * 8 - bits - 1;
48 const unsigned value = vpx_rb_read_literal(rb, bits + 1) << nbits;
49 return ((int) value) >> nbits;
50 #else
51 return vpx_rb_read_signed_literal(rb, bits);
52 #endif
53 }
54